JohnD Posted October 25, 2016 Share Posted October 25, 2016 I had a twilight race a couple of weekends ago, that started at 1730, so we had to show our lights on track.I was embarrassed to find that of the two left headlights, the outer was rather dim, while the inner, full beam light was fine.I had to race on sides, which is a different story.On investigation, I found that the earth wire had failed, completely separated from its connector far back in the loom, where it joined the earths from the other front lights.So both lights on that side were earthless - but they still worked! One not very well, but it was alight.There can be no earth through the bonnet - it's GRP.How is this possible? One light could, I suppose, find an earth through the other, but both at once? Full beam, Vitesse-style?All corrected now and working well, of course. I should have checked the lights before, especially as I knew of the special race regulation.Many classic car drivers only use them in good weather and day time. How long since you checked yours?JOhn Quote Link to comment Share on other sites More sharing options...
yorkshire_spam Posted October 25, 2016 Share Posted October 25, 2016 How is it possible?Depends on how it's wired John, but if the earths are joined, and the feed to 1 lamp is a few volts below the feed to the other then there's a small (couple of volts?) PD, so they'll be on but VERY dim. Quote Link to comment Share on other sites More sharing options...
JohnD Posted October 25, 2016 Author Share Posted October 25, 2016 The outer, dip/main,was dim. The inner,main only was as bright as the other side.But a 12v nominal supply to both lights, NO earth as the single earth wire or common to both.Where are the electrons going?John Quote Link to comment Share on other sites More sharing options...
Bitumen Boy Posted October 26, 2016 Share Posted October 26, 2016 I had a situation once where I eventually figured out that the lights were dim because the earth path was front indicator lamps > indicator wiring > rear indicator lamps > rear lamp unit earth. Could something like this be a possibility? Quote Link to comment Share on other sites More sharing options...
JohnD Posted October 26, 2016 Author Share Posted October 26, 2016 It's a GRP bonnet. No electrical connection, headlamps to sidelights.The only connections were three wires, two to supply dip and main lamps, and the earth, that wasn't connected.JOhn Quote Link to comment Share on other sites More sharing options...
esxefi Posted October 27, 2016 Share Posted October 27, 2016 you should have tried reversing the situation with the lights on the other side to see if they presented the same condition.there 'must' have been an earth somewhere or the lights could be wired in series but this would reduce the output of all of them a bit like fairy lights.could you draw a rough schematic of the wiring connections as i'm curious now.LOL Quote Link to comment Share on other sites More sharing options...
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